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## E. Boss, I Can See You!

Time limit: 1.0 second
Memory limit: 64 MB
— Oh, Boss, I can see you!
— Analogously!
From the animated film 'Investigation Held by Kolobki'
During their investigation, detectives Boss and Colleague got into an empty warehouse to look for evidence of crime. The warehouse is a polygon without self-intersections and self-tangencies, not necessarily convex. The detectives investigate the territory of warehouse in such a way that each of them can always see the other one. Boss and Colleague can see each other if all the points of a segment connecting them lie either inside the warehouse or on its border. Find the maximal possible distance between the detectives.

### Input

The first line of input contains an integer n: the number of vertices of the polygon (3 ≤ n ≤ 200). Next n lines contain two integers xi, yi each: coordinates of vertices in clockwise or counterclockwise order (−1000 ≤ xi, yi ≤ 1000). It is guaranteed that polygon has neither self-intersections nor self-tangencies.

### Output

Output the maximal possible distance between Boss and Colleague. The answer must be given with absolute or relative error not exceeding 10−6.

### Sample

inputoutput
```4
0 0
0 1
1 1
1 0
```
```1.414214
```
Problem Author: Mikhail Rubinchik (prepared by Egor Scshelkonogov)
Problem Source: Ural FU contest. Kontur Cup. Petrozavodsk training camp. Winter 2013
To submit the solution for this problem go to the Problem set: 1955. Boss, I Can See You!